Some countries in the Schengen visa-free travel zone have resumed checks at internal European borders, citing a rising number of undocumented migrants.

Slovakia on Wednesday said it would temporarily reinstate controls at its border with Hungary from Thursday.

It follows similar moves by Poland, the Czech Republic and Austria to tighten their borders with Slovakia.

Slovakia reported that around 40,000 undocumented migrants, mainly from the Middle East, entered the country since the beginning of the year, many coming through Hungary.

The controls include spot checks at road, rail and waterway crossings.

The announcement also came as EU ambassadors reached a deal on migration reform. 

'Chain reaction' of border controls

Slovak caretaker Prime Minister Ludovit Odor said his country had to introduce controls after its neighbors caused a "chain reaction."

"We prefer a European solution," he said.

Former Prime Minster Robert Fico, who is trying to form a ruling coalition after weekend parliamentary elections in Slovakia, said efforts to stem the flow of migrants would be one of his new government's priorities.

Wider European issue

Germany also introduced new controls with Poland and the Czech Republic last week.

National leaders of the EU's 27 member states are due to meet in the southern Spanish city of Granada on Thursday and Friday to discuss irregular migration, among other topics.

lo/sms (Reuters, dpa)